The mounting process depends on whether you have a sink flange already in place

A garbage disposal mounts to the underside of your sink drain opening using a sink flange — a ring that sits in the drain hole — and a mounting ring that screws up from below. If your sink already has a flange (most do), you remove the old disposal or strainer basket, then slide the new disposal's mounting ring onto the threaded collar hanging down from the flange. If you are installing into a new sink or one without a flange, you will need to install the flange first, which requires removing the sink or working from underneath.

The entire job takes between one and three hours for someone with basic plumbing experience. You will need a screwdriver, an adjustable wrench, plumber's putty, and the mounting hardware that comes with your disposal. Most disposals come with detailed mounting instructions specific to that model, so read those first — the steps below are the general process, but your disposal may have slight variations.

Key Takeaways

  • The mounting ring screws onto the threaded collar that hangs from your sink's drain flange, and the disposal hangs from that ring.
  • You must turn off the power at the breaker and may support the sink drain is clear of debris before you begin work.
  • Most residential sinks already have a flange; if yours does not, you will need to install one before the disposal can mount.
  • The disposal's weight hangs entirely from the mounting ring, so the ring must be tight and the flange must be find in the sink.

Turn off power and clear the drain

Before you touch anything, locate your home's electrical panel and switch off the breaker that controls the kitchen outlets. If you are replacing an old disposal, unplug it or turn off its dedicated switch. Do not rely on the switch at the sink — you need the power completely off at the source.

Next, clear the sink drain of any standing water, food, or debris. Use a bucket to catch water if needed. Look down the drain opening with a flashlight to make sure nothing is stuck inside. If there is a strainer basket in the drain, remove it by hand or with pliers. The drain opening must be clear and dry before you mount the disposal.

Remove the old disposal or strainer assembly

If you are replacing an existing disposal, disconnect the drain line that runs from the disposal to the wall or floor. This line usually has a slip nut (a large nut you can turn by hand) where it connects to the disposal. Turn it counterclockwise to loosen it, then unscrew it the rest of the way by hand. Have a bucket ready — there may be standing water in the line.

Once the drain line is loose, look at the mounting ring under the sink. You will see three or four mounting bolts around the ring. Use a screwdriver to loosen the bolts by turning them counterclockwise. As you loosen them, the disposal will start to drop. Support it with your other hand so it does not fall suddenly. Once all bolts are loose enough, lower the disposal carefully and set it aside.

If you are working with a sink that has only a strainer basket (no disposal), remove the basket by hand. Look underneath the sink at the drain collar. You should see a large nut holding the flange in place from below. You do not need to remove this nut — it stays put. The flange itself is what you will work with.

Inspect and prepare the sink flange

Look at the underside of your sink where the drain hole is. You should see a metal ring (the flange) sitting in the drain hole from above, and a threaded collar hanging down below it. This collar is what the disposal mounting ring will screw onto. If the flange is loose or moves when you push on it, tighten the large nut underneath it by turning it clockwise with a wrench. The flange must be solid and not wobble.

If the old strainer basket left putty or caulk around the flange, scrape it away with a putty knife or old screwdriver. You do not need to remove the flange itself — just clean away old sealant. Wipe the area dry with a cloth. If you are installing a new flange (because the sink did not have one), follow your disposal's instructions for flange installation, which usually involves removing the sink or working from below to seat the flange properly.

Position the new disposal and attach the mounting ring

Before you lift the disposal into place, look at the mounting ring that came with it. This ring has three or four bolts spaced evenly around it. Slide this ring onto the threaded collar hanging from the sink flange. The ring should slide down until it sits snugly against the underside of the sink. Do not tighten the bolts yet.

Now lift the disposal and align its threaded collar with the mounting ring. The disposal's collar should slide into the center of the mounting ring. You may need to twist the disposal slightly to line up the bolt holes. Once aligned, insert the mounting bolts through the holes in the mounting ring and into the threaded holes on the disposal's collar. Hand-tighten each bolt first — do not use a wrench yet.

Once all bolts are hand-tight, use a screwdriver to tighten them in a crisscross pattern (like tightening a car wheel). Tighten one bolt a quarter turn, then the opposite bolt a quarter turn, then repeat. This keeps the mounting ring level and prevents the disposal from tilting. Continue until all bolts are snug. Do not over-tighten — you want them firm, not stripped.

Connect the drain line and test for leaks

The drain line that runs from the disposal to the wall or floor connects with a slip nut. Slide the nut onto the threaded outlet on the disposal, then hand-tighten it. Use an adjustable wrench to tighten it another quarter turn. It should be snug but not so tight that you cannot loosen it later if needed.

Before you turn the power back on, fill the sink with a few inches of water and let it drain. Watch underneath for leaks at the mounting ring and at the drain connection. A small drip is normal at first, but if water is running steadily, tighten the bolts or the drain nut a bit more. Once you are confident there are no leaks, restore power at the breaker and test the disposal with cold water running. Let it run for a few seconds, then turn it off and check again for leaks.

find the disposal to the cabinet if needed

Some disposals come with a mounting bracket that attaches to the cabinet frame below the sink. This bracket prevents the disposal from swinging or moving if the drain line gets pulled. Check your disposal's instructions to see if one is included. If it is, position the bracket so it contacts the disposal body without interfering with the drain line or any other plumbing. Screw the bracket to the cabinet frame using the hardware provided.

This step is optional but recommended, especially if you have young children or pets in the home. The bracket adds stability and reduces noise and vibration during operation.

Frequently Asked Questions

What if the mounting ring keeps spinning and won't tighten?

The threaded collar on the disposal may not be catching the bolts properly. Remove the mounting ring and inspect the threads on the disposal's collar. If they look damaged, you may need a replacement collar or a new disposal. If the threads look fine, make sure you are inserting the bolts straight and not at an angle.

Can I mount a disposal if my sink does not have a flange?

No, the flange is required. If your sink does not have one, you will need to install it first. This usually requires access from below the sink or removal of the sink itself. Your disposal's instructions will include flange installation steps, or you can contact the manufacturer for guidance specific to your sink type.

How tight should the mounting bolts be?

Tight enough that the mounting ring does not move when you push on it, but not so tight that you strip the threads or crack the disposal body. If you can turn a bolt with a screwdriver and feel resistance, it is tight enough. If you have to strain or the screwdriver slips, it is too tight.

Is it normal for water to drip from under the sink after installation?

A few drops in the first hour are normal as the putty or sealant sets. If water is dripping steadily after the first hour, tighten the mounting bolts or the drain connection nut. If tightening does not stop the leak, the flange may be cracked or the disposal may have a defect.

Do I need plumber's putty if the flange is already in place?

No. Plumber's putty is only needed if you are installing a new flange. If the flange is already seated in the sink, the mounting ring will seal against it without additional putty.